Screw-propeller.



A. D. ISKOLS.

SCREW PROPELLER.

APPLICATION FILED NOV. 20. 1916.

1,245,234. Patented Nov. 6, 1917.

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UNITED STA'IES PATENT orrica ANATOL DAVID ISKOLS 0F SCHENECTADY, NEW YORK.

SCREW-PROPELLER.

To all whom it may concern:

Be it known that l, ANA'roL DAVID know, a citizen of the United States, resident of the city of Schenectady, county of Schenectady, State of New York, have invented certain new and useful improvements in Screw- Propellers, of which the following is a specification.

My invention relates to that type of screw propellers for ship propulsion where a hub carrying a certain number of helical blades is mounted on the end of the propeller shaft which is rotated by a reversible or non-reversible engine.

The present way of making screw propellers consists of making one side of the blades to conform to a true helical surface, this side is called the face of the blade, while the other side, called the back of the blade, is shaped more or less to an arc of a circle and is very far from being a helical surface.

As now constructed all the blades are attached to the hub with their faces or helical surfaces directed toward the stern, while their backs or arched sides are directed ahead or toward the bow. The result of this arrangement is that in going ahead the helical faces of the blades come into action exerting a thrust on the Water and the propeller, and if properly designed, show a high degree of efliciency, while in reversing the propeller and going astern the backs or arched surfaces of the blades come into action, exerting a thrust on the water in the opposite direction as before, but with a very low degree of efficiency, which is evidenced by the fact that ships going with full power astern show much less speed than when going ahead.

Evidently this is a great drawback, as in maneuvering, and is especially so when danger of a collision exists when it is of the greatest importance to have the screw propeller exert the greatest pull astern with the given engine power, or, in other words, to show as high an efficiency in going astern as when going ahead.

The object of my invention is to overcome the above drawbacks, and to provide a screw propeller with as high a degree of efficiency when reversed as when going ahead, and at the same time increasingthe efficiency in both directions.

For a consideration of what I believe to be novel and my invention, attention is di- Specification of Letters Patent.

Patented Nov. 6, 191 '7.

Application filed November 20, 1916. Serial No. 182,287.

rected to the accompanying description and the claims appended thereto.

In the accompanying drawing, which is illustrative of my invention, Figure 1 is a front view of a four-bladed screw propeller;

Fig. 2 is a vertical section through the same.

on line 22, Fig. l Fig. 3 is a horizontal axial section taken on line 3--3, Fig. 1; Fig. l is a front view of a three-bladed modification of my screw propeller; Fig. 5 is a vertical section through this propeller; Fig. 6 a horizontal section through a pair of blades at a certain distance from the center of the propeller, and Fig. 7 is an application of y invention to reversible screw propellers.

The hub 7, which is preferably shaped as a part of a spheroid and is fastened to the end of the tail shaft in the usual manner by means of a cone, feather key and nut, has four, or any even number of blades, of which blades 8 and 9 have their helical face directed toward the stern and arched back directed toward the bow, while blades 10 and 11 have their helical face directed toward the bow and their arched back directed toward the stern; in other words, they are turned around 180 with respect to blades 8 and 9.

This screw propeller operates in the following manner z-lVhen going ahead blades 8 and 9 come into action with their helical face producing the major part of the propeller thrust, while blades 10 and 11 operpropeller pull. By making blades 10 and 11 of the same pitch and area asthe blades 8 and 9, the propeller pull asternwill be of the same magnitude as the propeller thrust ahead, or by making blades 10 and 11 of a different pitch and larger area than blades 8 and 9 I can produce an even larger propeller pull astern than the propeller thrust ahead, as may be required for any particular ship or particular service. The four blades can be attached to the hub in the same vertical plane, that is, at the same distance from the end of the hub. But I prefer to offset them as shown in Figs. 2 and 3.

The blades can be cast in one with the hub as shown in Figs. 1 to 3, or separately and provided with flanges to be bolted to the hub, as shown in Fig. 5, or attached in any other suitable manner.

My invention can equally well be applied to reversible screw propellers of any type, and Fig. 7 shows the application to the simplest class of reversible propeller. Either single blades, or as shown in Fig. 7, double blades, 12, 13 are provided with a base or flange 14, wrist pin 13 pivoted in the hub,-

and crank 16 operate y any known and suitable mechanism in the usual way, that is, by being rotated through a certain angle.

What I claim as new and deslre to secure by Letters Patent of the United States, is 2- 1. A screw propeller having some of the blades with helical faces directed aft for going ahead, and others with helical faces directed toward the bow for going astern.

2. A screw propeller having some of the blades with helical faces directed aft for going ahead, and others with helical faces directed toward the bow for going astern, the blades for going astern being of differv vertical planes.

4. A screw propeller having double blades located one behind the other and having helical faces directed outwardly and arched backs facing each other.

5. A reversible'screw propeller comprising a hub, and blade rotatably pivoted on the hub, certain of the blades having helical faces directed aft and others having helical 'faces directed toward the bow.

6. A reversible screw propeller comprising a hub, and double blades rotatably pivoted on the hub, each double blade having helical faces directed outward and arched backs facing each other.

In witness whereof, I have hereunto set my hand this 14th day of November, 1916.

ANATOL DAVID ISKOLS. 

